JS: Time-based animation-pattern 2

tbanimation.js

var frames = {
	init: function() {
		$(window).on({
			'blur': frames.pause,
			'focus': frames.play
		});
		frames.play();
	},

	loop: function() {
		frames.setDelta();
		updateBackgrounds();
		frames.animationFrame = window.requestAnimationFrame(frames.loop);
	},

	setDelta: function() {
		frames.now = Date.now();
		frames.delta = (frames.now - frames.then) / 1000; // seconds since last frame
		frames.then = frames.now;
	},

	pause: function() {
		window.cancelAnimationFrame(frames.animationFrame);
		frames.areRunning = false;
	},

	play: function() {
		if(!frames.areRunning) {
			frames.then = Date.now();
			frames.loop();
			frames.areRunning = true;
		}
	}
};

var timer = 0;

var updateBackgrounds = function() {
	this.timer += frames.delta;
	if (this.timer > 0.1) {
		// Update background positions!
		this.timer = 0;
	}
};